Ammonia systems: efficiency and circuit management

In ammonia-based industrial refrigeration systems , efficiency depends not only on compressors, regulation, and control systems. The quality of the refrigerant and the internal conditions of the circuit can also significantly impact overall performance.

Air, water, oil, and other contaminants can alter evaporation and condensation conditions, increase the workload required by compressors, and promote malfunctions that, over time, result in higher consumption and reduced reliability. For this reason, in NH₃ systems , proper circuit management is a fundamental part of the energy efficiency strategy.

Air and non-condensable gases increase the condensation pressure

Among the most common contaminants in ammonia systems are non-condensable gases , primarily air . They can remain in the circuit after commissioning or enter during maintenance, system openings, or under certain pressure conditions.

The problem is linked to their behaviour in the condenser: since they cannot condense under normal operating conditions, they tend to accumulate on the high pressure side and can hinder heat exchange .

The consequence is an increase in pressure and condensation temperature , which forces the compressor to work under more demanding conditions. This reduces the efficiency of the refrigeration cycle and increases the electricity consumption required to produce the same amount of cold.

For this reason, manual or automatic purging systems for non-condensable gases become essential, especially in large industrial plants. A properly designed and positioned purger removes these gases, keeping the circuit as close to the conditions intended during the design phase as possible.

Water is a less obvious but equally critical contaminant

While the presence of air can be manifested by a relatively noticeable increase in condensation pressure, water contamination can be more difficult to detect.

In ammonia systems, water can enter during maintenance work, circuit modifications, or other operations that expose the system to the atmosphere. Once present, it can accumulate, especially in the low-pressure sections, and alter the properties of the refrigerant mixture.

Consequences may include:

• reduction in cooling capacity;
• worsening of cycle efficiency;
• alteration of the relationship between pressure and temperature;
• oil management problems;
• formation of residues or contaminants;
• worsening of heat exchange in evaporators.

This criticality is particularly important in large systems, where even a relatively small percentage loss in performance can translate into significant energy consumption on an annual basis.

Periodic monitoring of ammonia quality therefore becomes a preventative maintenance tool, not just an intervention to be carried out when the system already presents anomalies.

Efficiency means prevention before correction

The evolution of industrial refrigeration has led to the spread of increasingly advanced sensors, monitoring systems, and algorithms . These tools allow for the rapid identification of deviations from operating parameters, but digital data is no substitute for understanding the physical behavior of the system.

Abnormal pressure, a decreasing COP, or lower-than-expected cooling capacity are indeed symptoms. The true goal of maintenance should be to identify the underlying cause.

In ammonia systems, an effective strategy may include:

• periodic check for the presence of non-condensable gases;
• water contamination check;
• correct oil management and drainage;
• control of operating temperatures and pressures;
• comparison between real conditions and design parameters;
• analysis of performance trends over time;
• maintenance of automatic drain systems.

The principle is that of root cause analysis : avoid limiting yourself to replacing the component that is showing the fault and instead verify why that component has ended up working in abnormal conditions.

This approach reduces the risk of the problem recurring and allows the data collected by monitoring systems to be transformed into real optimization tools.

Ammonia and efficiency: the circuit must remain close to the design conditions

R717 continues to be one of the leading refrigerants in industrial refrigeration , thanks to its thermodynamic properties and virtually zero GWP. Its performance, however, also depends on the quality of the system's design, installation, and maintenance.

A system contaminated by air, water, or oil can progressively move away from its intended operating point, requiring more energy to maintain the same cooling load.

Circuit management must therefore be considered an integral part of energy efficiency: installing higher-performance components is not enough if the refrigerant and operating conditions are not kept under control.

For industrial refrigeration operators, the direction is therefore twofold: on the one hand, digitalization and monitoring, on the other, knowledge of physical phenomena, preventive maintenance, and correct fluid management.

It is through the integration of these two elements that ammonia systems can maintain efficiency, reliability and operational stability over time.